Corning Glass Works

Roger N Piasio

James W Ryan

James E Woiszwillo

Shirley A Mjos

Method of determining the presence and/or concentration of a polyvalent antigenic substance in a fluid. The method comprises the steps of incubating the fluid with labeled antibodies to the substance to form a first labeled immunochemical complex and then incubating that complex with immobilized antibodies to the substance to form a second labeled complex which is separated from the incubation medium. The amount of label in the second complex provides a means for detecting and/or quantitating the substance in the fluid. By reversing the sequence of incubation steps in a 'two-site' or sandwich assay, greater sensitivity is achieved and an intermediate washing step is eliminated.

Reverse sandwich immunoassay

Reagent and method for detecting the presence of hepatitis associated antigen (HAA) in blood serum. The reagent comprises anti-HAA antibodies coupled via an intermediate silane to a plurality of siliceous particles having a surface area of at least about 1 m.sup.2 /g and, if the particles are porous, an average pore diameter of at least about 1000 A. The test method comprises the steps of incubating a serum sample with the reagent to complex any HAA in the samplewith the antibodies of the reagent, incubating the reaction product with a solution of radio labelled anti-HAA antibodies to complex the labelled antibodies with any HAA that may be complexed to the reagent, separating the incubation products from the solution of labelled antibodies, and counting the radioactivity of either the separated products or the remaining solution to determine whether HAA was in the sample.

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Medfield, MA, United States of America

Roger N Piasio